Synthesis, crystal structure, and valence states of Mn-substituted<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>La</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>Ru</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:math>

Riegg, Stefan; García-García, Francisco J.; Reller, A.; Loidl, A.; Ebbinghaus, Stefan G.

doi:10.1103/physrevb.90.024406

Cited by 2 publications

(7 citation statements)

References 49 publications

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“…For y = 0.25, it was shown in Ref. [36] that only a fraction of the sample transforms to the lt structure, while about 55% remains in the ht modification (marked by the white shaded area in Fig. 11).…”

Section: Magnetic Phase Diagrammentioning

confidence: 92%

“…The paramagnetic moments increase almost linearly as a function of manganese concentration. With a valence of +4 for both ruthenium and manganese ions, as earlier determined by x-ray absorption near edge structure (XANES) measurements [36], paramagnetic moments of 2.83 μ B for ruthenium (S = 1) and 3.87 μ B for manganese ions (S = 3 2 ) are calculated. The theoretical expectation is shown as a solid line in Fig.…”

Section: Susceptibility and Magnetizationmentioning

confidence: 97%

“…A partial replacement of Ru 4+ with S = 1 by Mn 4+ with S = 3 2 is expected to have a strong influence on the singlet formation and to lead to a complex magnetic ground state. As spin dimerization and structural phase transition are intimately coupled, the effect of Mn substitution on the crystal structure in general and especially on the low-temperature structural transition was studied in detail using (synchrotron) x-ray and neutron diffraction [36]. For manganese substitution levels up to y = 0.2, a complete transition to the triclinic lt phase was observed, while for y = 0.25 only about 45% of the high-temperature phase transforms into the low-temperature modification, in which this characteristic dimerization occurs (Ref.…”

Section: A Magnetic Propertiesmentioning

confidence: 99%

“…For manganese substitution levels up to y = 0.2, a complete transition to the triclinic lt phase was observed, while for y = 0.25 only about 45% of the high-temperature phase transforms into the low-temperature modification, in which this characteristic dimerization occurs (Ref. [36]). susceptibility χ = M/H has been determined in an external field μ 0 H = 0.1 T for all concentrations.…”

Section: A Magnetic Propertiesmentioning

confidence: 99%

“…[36]). In addition, the valence states of Ru and Mn were determined by x-ray absorption spectroscopy documenting that both ions are purely tetravalent, at 300 K as well as at 110 K.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic and thermodynamic properties of the spin-dimer systemLa2RuO5induced by Mn substitution

et al. 2014

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Magnetic properties as well as the specific heat of the spin-dimer system La 2 Ru 1−y Mn y O 5 were investigated for manganese concentrations 0 y 0.25. The magnetic (dc) susceptibility of the unsubstituted (y = 0) system shows a steplike decrease close to 160 K reflecting a magnetostructural transition into a dimerized ground state. With increasing manganese concentration this behavior (typical for singlet formation) becomes continuously suppressed and the susceptibility bears the signatures of the emergence of new magnetic ground states. The high-temperature Curie-Weiss susceptibility can be described by Ru 4+ (S = 1) and Mn 4+ (S = 3 2 ) spin moments, with a dramatic decrease of the Curie-Weiss temperatures by almost 30% close to y = 0.1, indicating significant changes in the average mean magnetic exchange. Field-cooled and zero-field-cooled experiments as well as ac-susceptibility measurements provide clear evidence for the formation of a spin-glass state, well below the characteristic dimerization temperature. The relaxation dynamics can be described by a Vogel-Fulcher-Tammann behavior and indicates high fragility when characterized in terms of glassy dynamics of canonical supercooled liquids. Additional electron-spin resonance experiments indicate different spin-glass regimes and a rather dynamic nature of the dimerized phase. In the Mn-substituted compounds, a linear contribution to the heat capacity at low temperatures can be ascribed to the spin-glass formation. With increasing manganese concentration, the anomaly in the specific heat caused by the spin-singlet formation is shifted to lower temperatures and becomes continuously suppressed and smeared out. On the basis of these results, we propose a (y,T )-phase diagram indicating the competition of the spin-glass and the dimerized states. We stress the similarities with doped CuGeO 3 , the canonical inorganic spin-Peierls system.

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Section: Magnetic Phase Diagrammentioning

confidence: 92%

Section: Susceptibility and Magnetizationmentioning

confidence: 97%

Section: A Magnetic Propertiesmentioning

confidence: 99%

Section: A Magnetic Propertiesmentioning

confidence: 99%

“…[36]). In addition, the valence states of Ru and Mn were determined by x-ray absorption spectroscopy documenting that both ions are purely tetravalent, at 300 K as well as at 110 K.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic and thermodynamic properties of the spin-dimer systemLa2RuO5induced by Mn substitution

et al. 2014

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Unraveling Thermodynamics, Stability, and Oxygen Evolution Activity of Strontium Ruthenium Perovskite Oxide

et al. 2017

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Extensive investigations in understanding the functional mechanisms of metal oxides behind oxygen evolution have been carried out since an electrolyzer has demonstrated promising possibilities as a device to produce hydrogen for electrochemical energy conversion systems. In particular, perovskite oxides are reputable for high activity toward the oxygen evolution reaction (OER). Here, we revisited the list of active perovskite oxides constructed based on theoretical oxygen binding energies of reaction intermediates to the catalyst surface. From this list, Ru-based perovskites, i.e. SrRuO 3 and LaRuO 3 , have been predicted as active perovskites to exhibit a particularly high OER activity. We report on the stability of nanoscaled SrRuO 3 perovskite prepared by a simple and scalable flame synthesis method. Attempts to obtain LaRuO 3 were made; however, its DFT calculated phase diagram suggests that its perovskite phase is not thermodynamically stable, which supports our experimental results such that only a mixture of different La−Ru−O phases has been obtained. Nanoscaled SrRuO 3 is evaluated for its electrochemical activity with a particular emphasis pointed toward stability in both alkaline and acidic media. Through conjoining electrochemical methods, operando X-ray absorption spectroscopy (XAS), and theoretical calculations, we show that SrRuO 3 exhibits trivial activity toward OER that decreases promptly. The loss in activity is rationalized through DFT based computations, which corroboratively suggest the poor chemical stability of both selected perovskites. Regardless of the predicted theoretical OER activity, the intrinsic instability strongly suggests that Sr-and La-based ruthenium oxides are not viable catalysts for OER in aqueous media. This further suggests that their activities are independent of their binding energies between intermediates and catalyst surface but rather closely associated with material dissolution. We highlight that understanding the origin of stability under a real operating environment is absolutely essential for the design of a sustainable electrocatalyst with optimal balance between activity and stability.

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Synthesis, crystal structure, and valence states of Mn-substitutedLa2RuO5

Cited by 2 publications

References 49 publications

Magnetic and thermodynamic properties of the spin-dimer systemLa2RuO5induced by Mn substitution

Magnetic and thermodynamic properties of the spin-dimer systemLa2RuO5induced by Mn substitution

Unraveling Thermodynamics, Stability, and Oxygen Evolution Activity of Strontium Ruthenium Perovskite Oxide

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